1. Field of the Invention
The present invention relates to an automatic welding apparatus. More specifically, the present invention relates to a novel automatic welding apparatus, wherein a welding torch itself is used for sensing a welding line of a workpiece in an arc welding process.
2. Description of the Prior Art
An automatic welding apparatus of the play back type has been proposed and put into practical use, wherein a relative positional relation in the space between a welding torch and a workpiece is controlled in accordance with positional information and control information stored in a storage or a control apparatus, thereby to achieve an automatic welding process in accordance with a program. It has also been known to those skilled in the art that a sensor can be employed to make a welding torch trace a welding line of a workpiece. A conventional sensor for detecting a welding line of the workpiece was provided separately from the welding torch, but in the vicinity of the welding torch. As a result, the whole geometry of the welding torch was large. Therefore, it could happen that the welding torch, and thus the sensor do not reach the innermost recess of the workpiece, or the sensor does not effectively act on the welding line when the geometry of beveling or the angle of beveling is small. In addition, such a conventional apparatus is complicated in structure and expensive in cost, leaving various problems to be solved.